Organizing Committee


Poster Presentations

Poster Presentations


Genetic mapping of resistance to soybean rust (Phakopsora pachyrhizi Syd.) in the soybean cultivar DT2000

Presenter: T. D. Vuong

All authors and affiliations: T. D. VUONG (1), B. T. Nguyen (2), T. T. Vu (2), D. L. Hyten (3), P. B. Cregan (3), D. R. Walker (4), D. A. Sleper (1), J. G. Shannon (5), H. T. Nguyen (1). (1) Division of Plant Sciences and NCSB, University of Missouri, Columbia, MO; (2) National Plant Protection Institute (NPPI), Ha Noi, Vietnam; (3) Soybean Genomics and Improvement Lab, USDA-ARS, Beltsville, MD; (4) USDA-ARS and University of Illinois, Urbana, IL; (5) Division of Plant Sciences and NCSB, University of Missouri, Portageville, MO

Resistance to soybean rust (SBR) has been identified in many plant introductions (PIs) and is conferred by the single dominant genes Rpp15 and Rpp? (Hyuuga). However, the U.S. commercial cultivars are presumably susceptible to SBR. Among soybean germplasm evaluated for SBR resistance, the Vietnamese cultivar DT2000 has been consistently resistant to various SBR isolates. The objectives of the study were to identify and map genomic region(s) associated with the SBR resistance in DT2000. Two hundred thirty F6 recombinant inbred lines (RILs) from the Williams 82xDT2000 cross were phenotyped in Ha Noi, Vietnam, and Quincy, Florida, in 2008. Lesion type and disease severity (%) were recorded to assess responses of RILs to SBR. Based on lesion types, bulk segregant analysis (BSA) was conducted, and to detect potential quantitative resistance, selective genotyping was performed using RILs with higher and lower area under disease progress curve (AUDPC) values. The BSA results showed four BARC_SNP markers were positively clustered with the resistant bulk and DT2000 and mapped proximate to the Rpp3 locus on chromosome 6. However, a X2 test for lesion types indicated that DT2000 resistance was conditioned by a recessive gene that is not allelic to the known Rpp3 gene. For selective genotyping, the results indicated an additional region located on chromosome 18 was associated with variation in AUDPC values. It was concluded that in addition to qualitative inheritance of lesion type, DT2000 might have quantitative resistance to SBR.

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